As a control method for estimating parameters while stabilizing a control system, for a controlled target whose parameters are unknown, adaptive control is generally known. As a general adaptive control method, model reference adaptive control, self-tuning regulator, etc., are known. These adaptive control methods have a problem that since control algorithms are complicated and control parameters to be designed are numerous, it is difficult to adjust them.
As an adaptive control method for solving such a problem, there is known simple adaptive control (SAC) which assumes a model which realizes an ideal state and changes control parameters such that an actual output of a controlled target matches the model (see, e.g., Patent Literature 1). To enable the controlled target to be controlled by the SAC, it is required that ASPR (almost strictly positive real) condition be satisfied. To satisfy the ASPR, an output of a compensator called a parallel feed-forward compensator (PFC) is added to the output of the controlled target, which is known control.
However, in the above stated simple adaptive control which is somewhat simplified, there are still many parameters in design of the parallel feed-forward compensator, and therefore an expertise is needed. When consideration is given to a change in the controlled target and robustness of the control system, it is necessary to increase a compensation value output from the PFC to provide a design which gives importance to stability. However, this would degrade responsiveness. As a method of solving this problem, there is known a configuration in which gains of controlled target process are pre-stored, and modification values of PFC gains which are used in parallel feed-forward compensation computation are automatically adjusted based on the gains (see, e.g., Patent Literature 2), and a configuration in which model parameters of the controlled target are sequentially identified, and the PFC is sequentially adjusted according to a result of the identification (see, e.g., Patent Literature 3).